Radio-frequency switch



Jung 12, 1951 R. E. CHARLES RADIO-FREQUENCY SWITCH 5 Sheets-Sheet 1 Filed May 16. 1947 JNVENTOR. M

4 I I y June 12, 1951 Filed May 16, 194'? June 12, 1951 R. E. CHARLES 2,556,869

RADIO-FREQUENCY SWITCH F'il ed. May 16, 1947 5 Sheets-Sheet 3 June 12, 1951. R. E. CHARLES 2,556,869

RADIO-FREQUENCY SWITCH Filed May 16, 1947 5 Sheets-Sheet 4 FIG. IO

' June 12, 1951 RE, CH RLES 2,556,869

' RADIO-FREQUENCY SWITCH Filed May 16, 1947 5 SheetsSheet 5 \vk IIIIIIIIIIII\\\\\\\\\\\\\\\\\\\ IIIIIIIIIIIIII;)IIIIA 3 LLLL/I/I/ III INVENTOR. W 5 m Patented June 12, 1951 Randolph E. Charles,

Boston, Mass, assignor to General Communication Company, Boston, Mass, a. corporation of Massachusetts ApplicationMay 16, 1947, Serial No. 748,611-

Claims. 1

The art of transmission of very high frequency alternating electric currents has become highly developed within the last decade through the introduction of the coaxial line and the elimination of electrical losses which have attended the use of more primitive transmission techniques. Coaxial transmission lines may be described as two-wire electrical power lines made up of a tubular outer conductor containing a solid wire inner conductor, Various means being used to maintain constant insulation and central positioning of the inner conductor and, in some cases, flexibility ofthe line as a whole.

High frequency voltages and currents do not act in accordance with the customary concepts of two-wire electrical power transmission, and the success of coaxial transmission depends upon consistency of conductor dimensions, relative positioning, and the dielectrics present in the coaxial line itself. Any physical discontinuities in the structure of a coaxial line create standing waves, with consequent power losses as a result of wave reflections caused by such discontinuities. Switching facilities are, of course,. desirable-in coaxial transmission systems for various reasons as, for example, to switch an antenna between a radio transmitter and. receiver, as in radio telephone work, or to switch a radio transmitt'er or receiver from one antenna to another. Because of the difference in requirements of 'coaxial transmission, as compared to that of the more common commercial power circuits, switching devices for these high frequency lines must meet conditions very different from those in circuits transmitting low frequencies. In the latter a good electrical contactis the chief requirement. While this also is important in radio frequencies, it is equally important that switching apparatus used for the latter shall not introduce significant discontinuities or changes in characteristic line impedence. Power losses which might result from improperly designed switching apparatus should be entirely eliminated.

Other factors desirable in a satisfactory coaxial switch are low values of cross talk, or unintentional electrical interaction between cables not actually switched together. In some cases it is desirable, also, to provide for the shortcircuiting of cables not actually in use at all positions of the switch. Compactness of design and light weight are very desirable" for air craft and portable installations and a motor drive for the switches should be provided'in order to permit flexibility'of installation, to eliminate excess cabling, and for ease of control.

Similar switching problems also are encoun- 2 tered in connection with the newly developed wave guide power transmissiontechnique as used in radar work, where essentially the same consideration must be given to the matter of dimensions and continuit To devise switching apparatus which will sat isfy these requirements forms the chief object of the presentinvention.

The nature of the invention will bereadily unders'toodfrom the following description when read in connection with the accompanying drawings, and the novel features will beiparticularly pointed out in the appended claims.

In the drawings,

Fig. 1 is a perspective view of a switch constructed in accordance with this invention, some of the parts being broken away in order to illustrate concealed elements;

Fig. 2 is mainly a horizontal, sectional view of the switch shown in Fig. 1 but with some parts broken out, the plane of section being taken substantially along the axis of the inner conductor;

Fig. 3 is a vertical, sectional view of the switch shown in Fig. 1;

Fig. 4 is a perspective view of the base or body of the switch with some parts shown in section;

Fig. 5 is a-similar view of half of the rotor of the switch and .part of the. mechanism for operating it;

Fig. 6 is a perspective sectional view of parts of the clutch unit which forms one element of the switch operating mechanism;

Fig. 7 is a perspective view of the stop mechanism for the rotor;

Fig. 8 is a perspective, sectional view of the coupling for connecting the rotor with the axial terminal;

Fig. 9 isa perspective view showing some of the details ofthe switch operating mechanism;

Fig. 10: is a horizontaLsectional view of aswitch of thewave guide type embodying features of this invention;

Fig. 11: is a front elevation of the switch shown in Fig. 10;

Fig. 12 is a wiring diagram;

Fig. 13 is a top plan view of my invention; and

Figure 14 is a sectional elevation view of Fig.13.

Referring'fi'rst to Figs. 1, 2 and 3, the construction-there shown comprises a switch body 2 including a metal shell provided at its opposite ends which screw-threaded coupling elements 3 and 4 which form the outer elements of a coaxial conductor or conductors. The inner conductors are shown at 5 and 6, respectively, and they are insulated from the outer conductors by dielectric a modification of elements 1 and 8. Formed centrally in said body is a tapered or frusto-conical bore or socket, at the surface of which the coaxial stationary contacts of the switch terminate, these contacts being surface portions of the metal body 2 and the inner end surfaces of the conductors 5 and 6.

Mounted in the axial bore or socket of the switch body is a rotor tapered to fit the taper of the socket. It comprises a section of a coaxial conductor, the outer element of which is a metal shell I0, while its inner element is a conductor l2 including a radial arm and a vertical arm extending downwardly along the axis of the rotor. These parts l8 and !2 are separated by an insulating core l3 and those faces of the conductors at the right-hand end, Figs. 2 and 3, of the rotor, form coaxial contacts shaped and positioned for selective mating engagement with either of the two sets of stationary coaxial contacts above mentioned and which are. mounted in the switch body.

Preferably the inner conductor 12 of the rotor has some radial freedom of movement in the direction of its horizontal arm, and it is backed up by a short plug a, Figs. 2 and 5, against which a spiral spring It bears, this spring, in turn, being backed up by a screw plug [5 threaded into the shell ill of the rotor. This arrangement, therefore, forces the inner conductor radiallly in a direction to make a firm wiping contact with the inner conductor of either of the stationary terminals with which it is brought into register.

The input current is led axially into the switch body through a coupling,'one part of which consists of the fitting l5, Figs. 1 and 3, this fitting, like those shown at 3 and 4, being adapted to cooperate with one end of a coaxial cable coupling member of a common form. In this fitting Hi the center conductor IT is separated from the outer conductor by an insulator I8, and the upper end of this center conductor is shaped to form one member of a slip joint, the other member of this joint being the end portion of the downwardly extending arm of the rotor conductor i2. This slip joint is made such that the conductor l2 can revolve around the axis of the rotor while maintaining firm electrical contact with the stationary conductor H.

In order to produce good conduction through the stationary and movable contacts of this switch, when in mating engagement, the taper of the rotor and its socket in the switch body are made rather steep, say in the neighborhood of to 30 for the included angle, and a spring Washer 253 bears against the'lower end of the rotor where it forces it yieldingly upward and serves to maintain it normally in firm engagement with its seat in the switch body. This spring encircles, and is centered by, a metal sleeve 2! which extends downwardly from the rotor body, and a ball thrust bearing 22 backs up the spring 28 and is, itself, supported on an end plate 23 which is secured to the switch body 2 by screws 25-44, Fig. 3.

The end plate and the metal member of the l connector l6 preferably are either made integral or are welded together. Extending upwardly from the upper end of the part it is a split metal sleeve '25, best shown in Fig. 8, which fits releasably into the sleeve 2! of the switch body and 1 makes a firm, but yielding, contact with it, these parts forming the outer conductor of the axial input coupling.

It should be observed that the end of theinner rotor conductor l2 normally projects slightly beyond its insulation and the tapered face of the rotor. Also, that the contact ends of the inner radial conductors 5 and 6 project inwardly slightly beyond the tapered inner face of the socket in the switch body. This is also true of the contacting surfaces of the outer tubular terminals of said body. Consequently, when the rotor is revolved to bring its coaxial contacts good current-transmitting relationship to each other; Contributing to this result also is the fact that the lateral sides of the rotor at right angles to the horizontal axis of the'inner conductors 5 and 6 are spaced well away from the inner wall of the socket, as will be evident from an inspection of Fig. 2.

As above stated, it is desirable to have the switch power operated as, for example; to 'facilitate remote control. For this purpose the shell iii of the rotor is extended upwardly,'or has rigidly secured to it, a projecting portion forming a stem 26 and a circular flange 21, best shown in Fig. 5. Secured to thestem 26 by means of a'tapered pin 28 is the inner member 30 of a friction clutch, the outer member 3| of which is either made integral with, or is secured rigidly to, an internal gear 32', Figs. 3, 5 and 6. Meshing with this gear are two intermediate gears driven by a pinion 33 which is secured fast on the shaft of a small direct current motor 34 having permanent field magnets. Consequently, when the motor is running, the gear 32,'stem :26 and rotor it will be revolved in either aclockwise or counter-clockwise direction; depending I upon the position of the switch controlling the supply of energy to the motor.

The two parts of the clutch 30 and 3| are grooved on their meeting faces, as shown in Figs. 3 and 5, to receive a wire spring 35 which normally exerts enough friction on the two clutch members to make them rotate in unison. If the torque transmitted through the clutch becomes excessive, the outer member 3! will slip on the inner clutch disk 30.

Current is supplied to the motor-34 from any suitable direct current source, such as a 24 volt battery, through a reversing switch 3% and suitable connections leading. through the outlet 31 at the back of the switch body 2 to the stationary terminals 38 and39, respectively, Fig. 9, of two small switches 48 and fll which are mounted on an insulating disk 12 secured on the upper face of a top plate 33 which is welded to the body 2. These two switches are connected to the reversing [switch in the manner readily understood from Fig. 12, so that the motor will revolve in one direction or the other, depending upon the position of the switch 35. The switches A9 or 4! are limit switches, as will'presently be explained.

Small springs MI and M, Fig. 9, tendto hold their respective switches closed and either one is opened by swinging it inwardly.

In this particular construction the rotor is is revolved through and is thenstopped. When it is next started up, it is rotated in the opposite outlet end arrives in register with the selected terminal, the pin 66 will snap into the proper socket 67 due to the action of the spring 57.

With this construction switching can be made to a greater number of lines in a switch structure of a given size than Would be possible with the embodiment of the invention illustrated in Figs. 10 and 11.

It should also be noted that in the construction shown in Figs. 13 and 14 the passages in the radial arms are circular in cross-sectional form adjacent to the rotor 55, but their shape is gradually changed so that the ends of these terminals are of rectangular cross-sectional form to cooperate with tubular conductors of this form. In this sense these sections 52 to 55 may properly be termed transformer sections. In addition, the rotor is shaped in horizontal section, as shown in Fig. 2, so as to obtain the localized contact advantage.

From the foregoing it will be evident that this invention provides a radio frequency switch in which leakage of current and power losses are reduced to negligible values. The same is true of cross-talk. In addition, the invention may be embodied in designs exceptionally compact and light in weight. While in the particular form shown in Figs. 1, 2 and 3 only one input and two output terminals are provided, it is obvious that this number can be enlarged merely by inodifications in design. Thus the invention may be embodied in other forms without departing from the spirit or scope thereof.

Having thus described my invention, what I desire to claim as new is:

1. A radio frequency coaxial switch comprising a body provided with a socket, a rotor positioned in said socket, a center coaxial conductor section carried by the rotor and extending transversely of the axis thereof with one end exposed at a lateral surface of said rotor to form a coaxial rotor contact, a stationary coaxial terminal mounted radially with respect to said rotor in said body and having a coaxial contacting surface at the surface of said socket, said stationary and rotor contacts being positioned for mating engagement with each other at a predetermined point in the movement of said rotor around its axis, insulation surrounding said center conductor but permitting limited freedom of bodily movement of said conductor radially ofthe rotor, a portion of said insulation comprising a movable plug having an inner wall bearing against the inner end of the radially extending portion of said conductor and a spring bearing against an outer wall of said plug, said spring urging said conductor, through said plug, radially outward so that it makes a firm engagement with the center contact of said stationary terminal when in mating engagement with it.

2. A radio frequency coaxial switch comprising a, body provided with a tapered socket, a tapered rotor positioned in said socket, a center coaxial conductor carried by the rotor and having a section extending transversely of the axis thereof with one end exposed at a lateral tapered surface of said rotor and forming a coaxial rotor contact, a stationary coaxial terminal mounted radially with respect to said rotor in said body and having a coaxial contacting surface at the tapered surface of said socket, said stationary and rotor contacts being positioned for mating engagement with each other at a predetermined point in the movement of said rotor around its axis, said center conductor having another section, extending axially of said rotor, said sections having limited freedom of bodily movement relative to said insulation radially outward of the rotor, a movable plug of insulation having an inner wall bearing against the inner end of the radially extending section of said conductor and a spring mounted outside the path of current flow through said conductor and bearing against an outer wall of said plug and urging said conductor, through said plug, radially outward so that it makes a firm engagement with the center contact of said stationary terminal when in mating engagement with it.

3. A switch according to claim 2, in which said rotor has opposite end portions snugly fitting against the wall of the socket and the surface of the rotor which is between the end portions being spaced from the wall of the socket, whereby contact area of the rotor with the socket is mainly at the end regions of the rotor.

4. A switch according to preceding claim 2, in which the surfaces of said rotor between the area closely surrounding said rotor contact and that diametrically opposed to it are reduced in radial dimensions, thereby confining the pressure of the rotor on the wall of the socket mainly to the switch contact areas and points at the opposite side of the rotor axis from said contact areas.

5. A radio frequency coaxial switch comprising a body provided with a tapered socket, a tapered rotor positioned in said socket and including a center coaxial conductor with a section of the coaxial conductor positioned transversely of the axis of the rotor with one end exposed at a lateral tapered surface of said rotor and forming a co-- axial rotor contact, a stationary coaxial terminal mounted radially with respect to said rotor in said body and having coaxial contacting surfaces at the tapered surface of said socket, said stationary and rotor contacts being positioned for mating engagement with each other at a predetermined point in the movement of said rotor around its axis, the center conductor in said rotor having an arm extending along the axis of the rotor, an end plate secured to said switch body adjacent to one end of the rotor, and a coupling member projecting axially from said plate, said member including a flexible sleeve contact forming the outer conductor of an input'connection to the switch, and a flexible sleeve contact forming the center conductor of said input connection to the switch, said center conductor having a rotatable connection with said arm of the center conductor of the rotor.

RANDOLPH E. CHARLES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

